Forbes /Pharma & Healthcare /#PublicHealth
Mar 17, 2016 @ 11:55 AM
by Alice G. Walton
The biggest risk factors for Alzheimer’s disease are aging and genetic predisposition. That is, all of our risks go up as we get older, and those with certain genetic variants, like APOE e4, are also at heightened risk. But aside from these factors that we can’t control, there are some things that we do in the way of activities and lifestyle, which seem to affect our risk, both for better and for worse. Research has found that different factors are linked to Alzheimer’s, depending on how they influence our neurology, metabolisms, immune systems and cardiovascular systems. The caveat is that while they may not affect whether plaques and tangles accumulate in our brains, they may at least affect the speed with which they do, the age at which they do and our ability to cope with them.
Here are the things studies suggest may actually affect our risk of Alzheimer’s down the road. There’s no magic bullet, but doing as many of these as you can may make a difference over the years.
Food has long been thought to be linked to brain health. It’s not totally clear whether specific foods can reduce a person’s risk of Alzheimer’s, but overall diet may have an effect. For instance, a new study in The Journal of the American Medical Association found that fish, regardless of mercury level, was linked to reduced risk for Alzheimer’s, but only for those with a strong genetic predisposition. On the other hand, some researchers say there’s no really convincing evidence that any one food alone can affect anyone’s risk across the board.
But again, one’s whole diet may have an effect, at least on how and when symptoms onset, over the years. In fact, the central aim of the MIND diet, ranked high by U.S. News and World Reports in ease of follow-ability and healthiness, is to reduce one’s risk of dementia. A study last year by the Rush University researchers who developed it showed that people who followed the diet most closely over about 4.5 years cut their risk of dementia by over 50%. Those who followed it even moderately were at a 35% reduced risk.
According to the diet, the foods to eat in abundance are: Green leafy vegetables; any other types of vegetable; nuts; berries, and in particular blueberries; beans; whole grains; fish; poultry; olive oil; and a little wine. And those to avoid: Red meats, butter and stick margarine, cheese, pastries and other sweets, and fried or fast food.
Notice that this all sounds much like the oft-hailed Mediterranean diet: In fact, the MIND diet is a hybrid of the heart-healthy DASH diet and the Mediterranean diet, which itself has been linked to reduced risk of cognitive decline and even progression to Alzheimer’s. But it’s not clear whether single components of the diet are enough to affect Alzheimer’s risk. Where some studies have suggested so–like the fish study above, or this recent one, finding that blueberry extract may have an effect–not everyone agrees.
“I think the diet fads of blueberries, broccoli, coffee are all nonsense,” says David S. Knopman, researcher at the Mayo Clinic. “No one eats food in isolation, and trying to disentangle associations between foods, especially when all the data is observational, is a hopeless and useless task.”
So take this as you will. Diet as a whole may reduce one’s symptoms of dementia or delay onset, but it’s unlikely that eating fish or blueberries alone, if you’re not doing other things as well, will do much at all.
The connection between exercise and brain health is quite strong, and the research keeps confirming it. Exercise increases blood flow and oxygen to the brain, which may underlie the connection. It also seems to help generate new neurons, particularly in the brain’s hippocampus, the area that governs learning and memory, and which is known to lose volume with age–and in Alzheimer’s disease. Some studies have found that in people with genetic risk for the disease, exercise may help preserve the volume of the hippocampus over time. Others have suggested that exercise may delay the onset or reduce the risk of the disease later in life. Though researchers are loath to say it will unequivocally reduce a person’s risk, it certainly seems like a good candidate in preventing Alzheimer’s in general.
And what may really explain the link between exercise and dementia is the undeniable connection between the heart and the brain–so that what’s good for the one is good for the other, and what hurts the one hurts the other. Smoking, for instance, is linked to heart attack and to dementia–so are being overweight, obese, sedentary, having high blood pressure and having diabetes. So doing right by your heart in all the ways we know about–food, lifestyle choices and exercise–will do well for your brain as well.
“Presumably, all of these lifestyle factors have the common thread of being related to cardiovascular and cerebrovascular disease,” says Knopman. “And it is thought that reducing exposure to the bad ones and increasing exposure to the good ones (i.e., exercise) reduce one’s burden of cerebrovascular disease, which in turn reduces the brain injury that is caused by cerebrovascular disease (i.e., overt strokes and the covert deterioration of blood vessels (generally smaller or microscopic ones) that are key to maintaining the brain’s nutrition.”
In other words, exercise–and, in some sense, most of these lifestyle factors–may boil down the cardiovascular connection. There’s even been some evidence that coffee is linked to reduced dementia risk, but it may just be its connection to cardiovascular health, which it’s been shown to have in recent years.
We often hear that crosswords and Sudoku can stave off dementia, but there’s been mixed evidence about how activities like these really affect risk. A recent study in The New England Journal of Medicine got some attention when it reported that Alzheimer’s in people who had at least a high school education has declined over the years, relative to those who had less education, suggesting that education may have some protective effect.
Another new study finds that people who were educated, stayed mentally active in middle age and who had higher genetic risk for Alzheimer’s had less amyloid plaque buildup in their brains than people who didn’t stay mentally active. The link is not so clear for people without the gene.
“There is substantial evidence that these activities help to delay the onset of memory and thinking problems,” said study author Prashanthi Vemuri. “What we don’t know is how this process works.” And what we also don’t know is which way the connection goes–it’s possible that people who already had plaques in their brains stopped to be mentally active because of it. But we’ll need more research to understand it more clearly.”
Knopman adds that it’s best if mental stimulation is a lifelong endeavor, rather than a late-in-life one, since at that point it may be too little too late. “The key thing to keep in mind with these sorts of activities is that they invariably originate from exposure and lifestyle choices early in life,” he says, “so that late life cognitive and social activities are invariably reflections of life-long activities. Presumably these activities can stimulate the development of new and enriched brain connectivity, which in turn might protect a person from becoming demented by increasing the amount of reserve that the brain possesses.”
In other words, people with more education or richer intellectual lives may be able to better withstand the effects of Alzheimer’s, since they have more reserves to use when the disease hits. “It is not that the cognitive activity stops amyloid beta production or neurofibrillary tangle development or spread,” says Knopman, “but rather that higher cognitive activity endows the brain with a greater ability to endure the effects of brain pathologies compared to a person with lower cognitive engagement throughout life.”
For reasons that aren’t totally understood, mental health issues like depression and chronic stress have been linked to Alzheimer’s disease in some studies. It’s not totally clear which came first, the chicken or the egg. It could be that depression and stress are actually very early symptoms of the disease–or it could be that either one alone actually raises the risk for dementia, because of the ways in which they change or inflame the brain. Or perhaps experiencing mental health issues just makes a person less resilient, just like mental activity makes a person more so. But taking care of your mental health, whether or not it’s linked to dementia, is always important.
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So these are some of the ways in which lifestyle can affect risk. Some research has suggested that incorporating healthy lifestyle factors and reducing the bad ones could reduce the risk of dementia by up to two-thirds. Whether it would be that much is unclear, but doing the good things we know to do will very likely help. We may not know by how much they’ll help, but at this point, we do know that they do.